I'm working on a project, which contains a DFPlayer Mini: Reference

However, while the I2C modules are working great, i can't get the DF to work (Serial communication). It won't recognized by the Arduino board, and it does literally nothing.

I wired the module according to the connection diagram (see Reference above), loaded up the sample code, but this gives me just "Unable to begin ..."

What i already tried:

  • At first, i'll integrated the DF module in my existing circuit; so i seperated it from this and wired it up on a breadboard (Standalone).
  • As the result was the same, i soldered the wires directly, to eliminate the "source of error" breadboard.
  • My main platform is a Teensy 2.0; however, i tried an Arduino Micro, and now a Arduino Mega 2560.
  • I bought another two DF modules and ended up having three of them, all with the same result.
  • I tried both powering the module (3.3V and 5V) from an external power source, or the Arduino.
  • Starting with SoftwareSerial, i tried (on all three boards) different TX / RX pins, using Serial1, Serial2, no luck.
  • Put a 1k resistor between RX or TX or both.
  • However, if i connect IO_1 and GND on the DF module (button), the LED turns on, but nothing happens.

The current setup is on the Arduino Mega, wired up DF-TX to TX1 (Pin 18), DF-RX to RX1 (Pin 19, with 1k resistor), DF-VCC and DF-GND to an external power source (5V). Also, i connected a speaker (4 Ohms, 3W) to the player. SD card (4GB) is formatted with FAT (also tried FAT32), contains a mp3 folder with three files named 0001.mp3, 0002.mp3 and 0003.mp3. The Arduino itself is currently powered by USB.

Does anyone have an idea how to get the serial communication (or the module itself) working?

Edit: Source Code, which i used as "base"

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